New Informa Journal Article Clarifies Understanding Of Post-Operative Visual Loss

Main Category: Eye Health / Blindness
Article Date: 13 Oct 2008 - 4:00 PDT

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Reports of loss of vision after non-ocular surgery have been increasing over the last fifteen years and, though it is a relatively uncommon complication, experts are keen to understand why and how often it happens because of the devastating impact on a patient's quality of life and for the medicolegal implications for surgeons and patients alike. A new article, written by Molly E. Gilbert, MD, from the University of Illinois Eye and Ear Infirmary, in Informa's Journal Neuro-Ophthalmology, provides a clear and thorough review of the studies, findings and current literature on the subject - as well as providing recommendations for surgical teams in preventing this tragic complication.

The report covers the results of two large retrospective studies which show that post-operative visual loss (POVL) can be as high as 4.5% in cardiac surgery and 0.2% in spine surgery.

"Determining the actual overall incidence of POVL is difficult since it is not known what percentage of cases is reported," explains the author of the article, Molly E. Gilbert, MD. "A wide variety of surgical interventions have been associated with POVL, including cardiopulmonary bypass, lumbar spine surgery, neck dissection, abdominal procedures, hip surgery, cholecystectomy, parathyroidectomy, prostate surgery, pleurodesis and rotator cuff surgery."

There a several causes of POVL after non-ocular surgery, including ischemic optic neuropathy, central retinal artery or vein occlusion and cortical blindness. "A variety of factors have been identified that contribute to the various causes of POVL - some of these are intrinsic to the patient and may be thought of as predisposing factors, while others are related more directly to surgery and anesthesia," explains Dr Gilbert.

Any interruption of blood supply to the eyes during surgery - whether this is caused by pressure to the eye itself or to the blood supply - or an interruption to the patient's blood flow autoregulation system can lead to POVL. One study showed that there was a higher increase of intraocular pressure (IOP) in patients whose heads were supported by pillows versus patients whose heads were supported by pins in the prone position. Another study demonstrated that time as time spent in the prone position increased, IOP continued to increase as well. Some authors have suggested that IOP may increase as a result of large amounts of intravenous fluids given during surgery.

"Certainly, the studies seem to show that the duration of anesthesia is an independent risk factor for eye injury," explains Dr Gilbert. "The risk is increased further with endotracheal intubation and in patients undergoing surgery of the head or neck."

Reports from the Scoliosis Research Study of POVL concluded that consideration should be given to establishing a minimum systolic blood pressure for each patient as well as staging long procedures and protecting eye position during surgery. The American Society of Anesthesiologists has established a POVL registry and has identified the risks of prone positioning, blood loss and long surgical times.

"A variety of factors make POVL difficult to predict and prevent," says Dr Gilbert. "Many patients have certain clinical factors that could predispose them to developing POVL. In addition, many surgeries use deliberate hypotension, prone positioning, long surgical times, or are associated with significant blood loss without leading to POVL.

"Based on the information that is currently available, there is no good treatment for POVL. Therefore, education of colleagues in anesthesia and surgery is essential to help prevent this devastating complication," explains Dr Gilbert.

Recommendations include:

1. Careful preoperative history to identify any pre-existing patient risk factors that predispose to POVL.
2. Considered use of deliberate hypotension in patients at risk.
3. Avoidance of compression of eye, abdomen or chest in patients placed prone.
4. Correction of anemia and/or hypotension as early as is feasible upon identification of these risk factors.

"Postoperative Visual Loss: A Review of the Current Literature"
Molly E. Gilbert
Neuro-Ophthalmology, 32:194-199, 2008
Click here to view article (PDF)

About the Author

Molly E. Gilbert MD is an assistant professor of ophthalmology at the University of Illinois-Chicago Eye and Ear Infirmary. She completed an eighteen month fellowship in neuro-ophthalmology at Wills Eye Institute.

About Neuro-Ophthalmology

Providing an outlet for international research, Neuro-Ophthalmology publishes original papers on diagnostic methods such as visual fields, neuro-imaging and electrophysiology; the visual system such as the retina, oculomotor system, pupil, neuro-ophthalmic aspects of the orbit, and related fields such as migraine and ocular manifestation of neurological diseases.